In his new book, Exultant Ark, animal behaviourist Jonathan Balcombe argues that animals experience pleasure, comfort and joy and that these traits are more than just practical evolutionary survival adaptations.

From foraging pikas to paw-in-paw sea otters, the personalities of creatures are brought to life through emotive and compelling images. Here are some of our favourites.

This juvenile great blue heron (Ardea herodias), photographed in San Carlos Bay, Florida, has an itch. Balcombe suggests that scratching may bring this heron the pleasure of relief, much as it can in humans.